U.S. patent number 6,331,488 [Application Number 08/862,752] was granted by the patent office on 2001-12-18 for planarization process for semiconductor substrates.
This patent grant is currently assigned to Micron Technology, Inc.. Invention is credited to Guy T. Blalock, Trung T. Doan, Mark Durcan, Scott G. Meikle.
United States Patent |
6,331,488 |
Doan , et al. |
December 18, 2001 |
Planarization process for semiconductor substrates
Abstract
A method of manufacturing semiconductor devices using an
improved chemical mechanical planarization process for the
planarization of the surfaces of the wafer on which the
semiconductor devices are formed. The improved chemical mechanical
planarization process includes the formation of a flat planar
surface from a deformable coating on the surface of the wafer
filling in between the surface irregularities prior to the
planarization of the surface through a chemical mechanical
planarization process.
Inventors: |
Doan; Trung T. (Boise, ID),
Blalock; Guy T. (Boise, ID), Durcan; Mark (Boise,
ID), Meikle; Scott G. (Boise, ID) |
Assignee: |
Micron Technology, Inc. (Boise,
ID)
|
Family
ID: |
25339249 |
Appl.
No.: |
08/862,752 |
Filed: |
May 23, 1997 |
Current U.S.
Class: |
438/698; 216/87;
427/278; 438/692; 438/760; 438/705; 427/370; 427/277; 216/88;
257/E21.244 |
Current CPC
Class: |
H01L
21/31053 (20130101) |
Current International
Class: |
H01L
21/3105 (20060101); H01L 21/02 (20060101); H01L
021/302 (); B05D 003/00 () |
Field of
Search: |
;427/277,278,370
;216/87,88,89,95,96,97,13,53,54
;438/694,697,698,705,759,760,692 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
285245 |
|
Oct 1988 |
|
EP |
|
683 511 A2 |
|
Nov 1995 |
|
EP |
|
0683511A3 |
|
Nov 1995 |
|
EP |
|
731503A2 |
|
Sep 1996 |
|
EP |
|
998210 |
|
Jul 1965 |
|
GB |
|
90/12683 |
|
Nov 1990 |
|
WO |
|
Other References
Supplementary European Search Report, dated Feb. 17, 2000. .
Exhibit A, 2 pages. .
Cameron et al., "Photogeneration of Organic Bases from
o-Nitrobenzyl-Derived Carbamates," J. Am. Chem. Soc., 1991, 113,
pp. 4303-4313. .
Cameron et al., "Base Catalysis in Imaging Materials," J. Org.
Chem., 1990, 55, pp. 5919-5922. .
Allen et al., "Photoresists for 193-nm Lithography," IBM J. Res.
Develop., vol. 41, No. 1/2, Jan.-Mar. 1997, pp. 95-104. .
Seeger et al., "Thin-Film Imaging: Past, Present: Prognosis," IBM
J. Res. Develop., vol. 41, No. 1/2, Jan.-Mar. 1997, pp. 105-118.
.
Shaw et al., "Negative Photoresists for Optical Lithography," IBM
J. Res. Develop., vol. 41, No. 1/2, Jan.-Mar. 1997, pp. 81-94.
.
Ito, H., "Chemical Amplification Resists: History and Development
Within IBM," IBM J. Res. Develop., vol. 41, No. 1/2, Jan.-Mar.
1997, pp. 69-80. .
Rothschild et al., "Lithography at a Wavelength of 193 nm," IBM J.
Res. Develop., vol. 41, No. 1/2, Jan.-Mar. 1997, pp.
49-55..
|
Primary Examiner: Mills; Gregory
Assistant Examiner: Goudreau; George
Attorney, Agent or Firm: TraskBritt
Claims
What is claimed is:
1. A method for planarizing a non-planar film surface of a wafer,
said method comprising the steps of:
providing a wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object;
forming a substantially flat planar surface on said non-planar film
surface of said wafer;
performing one of group of curing, hardening, and solidifying the
deformable material while the object is contacting the deformable
material; and
planarizing said wafer using a chemical mechanical planarization
process.
2. A method for planarizing a non-planar film surface of a wafer,
said method comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object;
forming a substantially flat planar surface on said non-planar film
surface of said wafer;
hardening the deformable material while the object contacts the
deformable material; and
planarizing said wafer using a chemical mechanical planarization
process.
3. A method for planarizing a non-planar film surface of a wafer,
said method comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object;
forming a substantially flat planar surface on said non-planar film
surface of said wafer;
solidifying the deformable material while the object contacts the
deformable material; and
planarizing said wafer using a chemical mechanical planarization
process.
4. A method for planarizing a non-planar film surface of a wafer,
said method comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object, the object
including a shaped surface thereon contacting the deformable
material, the shaped surface including a convex surface
portion;
forming a substantially flat planar surface on said non-planar film
surface of said wafer; and
planarizing said wafer using a chemical mechanical planarization
process.
5. A method for planarizing a non-planar film surface of a wafer,
said method comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object, the object
including a shaped surface thereon contacting the deformable
material, the shaped surface including a concave surface
portion;
forming a substantially flat planar surface on said non-planar film
surface of said wafer; and
planarizing said wafer using a chemical mechanical planarization
process.
6. A method for planarizing a non-planar film surface of a wafer,
said method comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object, the object
including a shaped surface thereon contacting the deformable
material, the shaped surface including a convex surface portion and
a concave surface portion;
forming a substantially flat planar surface on said non-planar film
surface of said wafer; and
planarizing said wafer using a chemical mechanical planarization
process.
7. A method for planarizing a non-planar film surface of a wafer,
said method comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object, the object
including a shaped surface thereon contacting the deformable
material, the object including a flat optical glass object;
forming a substantially flat planar surface on said non-planar film
surface of said wafer; and
planarizing said wafer using a chemical mechanical planarization
process.
8. A method for planarizing a non-planar film surface of a wafer,
said method comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
coating the object with a release agent prior to contacting the
deformable material;
contacting the deformable material with an object, the object
including a shaped surface thereon contacting the deformable
material;
forming a substantially flat planar surface on said non-planar film
surface of said wafer; and
planarizing said wafer using a chemical mechanical planarization
process.
9. A method for planarizing a non-planar film surface of a wafer
having at least one electrical circuit formed thereon, said method
comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object;
forming a substantially flat planar surface on said non-planar film
surface of said wafer; curing the deformable material while the
object contacts the deformable material; and
planarizing said substantially flat planar surface on said wafer
using a chemical mechanical planarization process.
10. A method for planarizing a non-planar film surface of a wafer
having at least one electrical circuit formed thereon, said method
comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object;
forming a substantially flat planar surface on said non-planar film
surface of said wafer;
hardening the deformable material while the object contacts the
deformable material; and
planarizing said substantially flat planar surface on said wafer
using a chemical mechanical planarization process.
11. A method for planarizing a non-planar film surface of a
wafer
having at least one electrical circuit formed thereon, said method
comprising:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object;
forming a substantially flat planar surface on said non-planar film
surface of said wafer; solidifying the deformable material while
the object contacts the deformable material; and
planarizing said substantially flat planar surface on said wafer
using a chemical mechanical planarization process.
12. A method for planarizing a non-planar film surface of a wafer
having at least one electrical circuit formed thereon, said method
comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object, the object
including a shaped surface thereon contacting the deformable
material, the shaped surface including a convex surface
portion;
forming a substantially flat planar surface on said non-planar film
surface of said wafer; and
planarizing said substantially flat planar surface on said wafer
using a chemical mechanical planarization process.
13. A method for planarizing a non-planar film surface of a wafer
having at least one electrical circuit formed thereon, said method
comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object, the object
including a shaped surface thereon contacting the deformable
material, the shaped surface includes a concave surface
portion;
forming a substantially flat planar surface on said non-planar film
surface of said wafer; and
planarizing said substantially flat planar surface on said wafer
using a chemical mechanical planarization process.
14. A method for planarizing a non-planar film surface of a wafer
having at least one electrical circuit formed thereon, said method
comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object, the object
including a shaped surface thereon contacting the deformable
material, the shaped surface includes a convex surface portion and
a concave surface portion;
forming a substantially flat planar surface on said non-planar film
surface of said wafer; and
planarizing said substantially flat planar surface on said wafer
using a chemical mechanical planarization process.
15. A method for planarizing a non-planar film surface of a wafer
having at least one electrical circuit formed thereon, said method
comprising the steps of:
providing said wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object, the object
including a flat optical glass object;
forming a substantially flat planar surface on said non-planar film
surface of said wafer; and
planarizing said substantially flat planar surface on said wafer
using a chemical mechanical planarization process.
16. A method for planarizing a non-planar film surface of a wafer
having at least one electrical circuit formed thereon, said method
comprising:
providing said wafer;
providing an object;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object;
forming a substantially flat planar surface on said non-planer film
surface of said wafer; and
planarizing said substantially flat planar surface on said wafer
using a chemical mechanical planarization process.
17. A method for planarizing a non-planar film surface of a wafer,
said method comprising the steps of:
providing an object having a flat planar surface thereon;
providing said wafer;
applying a deformable material to said non-planar film surface of
said wafer;
contacting the deformable material with the object;
forming a substantially flat planar surface on said deformable
material on said non-planer film surface of said wafer; and
subsequently
planarizing said wafer using a chemical mechanical planarization
process.
18. A method for planarizing a non-planar film surface of a wafer,
said method comprising the steps of:
providing said wafer;
providing an object having a flat planar surface thereon;
providing a flexible resilient member at the back of the wafer;
applying a deformable material to said non-planar film surface of
said wafer;
contacting the deformable material;
forming a substantially flat planar surface on said deformable
material on said non-planer film surface of said wafer; and
subsequently
planarizing said wafer using a chemical mechanical planarization
process.
19. The method of claim 18, wherein said deformable material is
contacted by an object.
20. A method for planarizing a non-planar surface of a wafer, said
method comprising the steps of:
providing an object having a flat planar surface thereon;
providing said wafer;
applying a deformable material to said non-planar surface of said
wafer;
contacting the deformable material with the object;
forming a substantially flat planar surface on said deformable
material on said non-planar surface of said wafer; and
subsequently
planarizing said wafer using a chemical mechanical planarization
process.
21. A method for planarizing a non-planar surface of a wafer, said
method comprising:
providing said wafer;
providing an object having a flat planar surface thereon;
providing a flexible resilient member at the back of the wafer;
applying a deformable material to said non-planar surface of said
wafer;
contacting the deformable material with said object;
forming a substantially flat planar surface on said deformable
material on said non-planar surface of said wafer; and
subsequently
planarizing said wafer using a chemical mechanical planarization
process.
22. A method for planarizing a non-planar surface of a wafer, said
method comprising:
providing said wafer;
providing an object having a flat planar surface thereon;
providing a flexible resilient member;
applying a deformable material to said non-planar surface of said
wafer;
contacting the back of the wafer with the flexible resilient
member;
applying pressure to the deformable material with said object;
forming a substantially flat planar surface on said deformable
material on said non-planar surface of said wafer; and
planarizing said wafer using a chemical mechanical planarization
process.
23. The method of claim 1, further comprising the step of:
applying a substantially uniform pressure to the deformable
material on the non-planar film surface of the wafer to form a
substantially flat planar surface on the deformable material.
24. A method for planarizing a non-planar surface of a wafer, said
method comprising the steps of:
providing said wafer;
providing an object having a flat planar surface thereon;
providing a flexible resilient member at the back of the wafer;
applying a deformable material to said non-planar surface of said
wafer;
contacting the deformable material;
forming a substantially flat planar surface on said deformable
material on said non-planer surface of said wafer; and
subsequently
planarizing said substantially flat planar surface on said
deformable material on said non-planar surface of said wafer using
a chemical mechanical planarization process.
25. The method of claim 1, further comprising the step of:
applying a substantially uniform pressure to the object while the
object is in contact with the deformable material.
26. A method for planarizing a non-planar film surface of a wafer
having at least one electrical circuit formed thereon, said method
comprising the steps of:
providing a wafer;
coating said surface of said wafer with a deformable material;
contacting the deformable material with an object;
forming a substantially flat planar surface on said non-planar film
surface of said wafer by performing one of curing, hardening, and
solidifying the deformable material while the object contacts the
deformable material; and
planarizing said substantially flat planar surface on said wafer
using a chemical mechanical planarization process.
27. The method of claim 1, further comprising the step of:
applying a substantially uniform pressure to the deformable
material on the non-planer film surface of the wafer to form a
substantially flat planar surface on the deformable material.
28. The method of claim 1, wherein the object comprises a
substantially inflexible object having a flat surface thereon.
29. The method of claim 1, further comprising the step of:
contacting the wafer with a resilient member.
30. The method of claim 29, wherein the back of the wafer is
contacted with said resilient member.
31. The method of claim 29, further comprising the step of:
applying pressure to the resilient member to form a substantially
flat planar surface on the deformable material.
32. The method of claim 31, further comprising the steps of:
contacting the resilient member with a substrate; and
applying pressure to the substrate thereby applying pressure to the
resilient member.
33. The method of claim 31, further comprising the steps of:
applying pressure to the wafer through the resilient member thereby
applying pressure to the object thereby deforming the coating of
deformable material on the wafer.
34. The method of claim 1, wherein said wafer comprises a wafer
having electrical circuit components on a surface thereof.
35. The method of claim 1, wherein said wafer comprises a wafer
having a plurality of electrical circuit components on a surface
thereof and a coating substantially covering the electrical circuit
components.
36. The method of claim 1, wherein said wafer comprises a wafer
having a plurality of electrical components on a surface thereof
and a coating substantially covering the electrical components and
said wafer.
37. The method of claim 1, further comprising the step of:
applying a substantially uniform pressure to the object while the
object is in contact with the deformable material.
38. The method of claim 1, further comprising the step of:
applying pressure to the object while the object contacts the
deformable material.
39. The method of claim 1, further comprising the step of:
applying pressure to the coating of deformable material on the
non-planer surface of the wafer while the object contacts the
deformable material.
40. The method of claim 1, wherein the object includes a
substantially flat planar surface thereon contacting the deformable
material.
41. The method of claim 1, further comprising the step of:
applying pressure to the object while the object contacts the
deformable material.
42. The method of claim 1, further comprising the step of:
applying pressure to the coating of deformable material on the
non-planer film surface of the wafer while the object contacts the
deformable material.
43. The method of claim 1, wherein the object includes a
substantially flat planar surface thereon contacting the deformable
material.
44. The method of claim 1, wherein the object includes a shaped
surface thereon contacting the deformable material.
45. The method of claim 44, wherein the shaped surface comprises a
desired shaped surface.
46. The method of claim 1, wherein the object includes a
substantially inflexible object.
47. The method of claim 1, further comprising the step of:
contacting the wafer with a resilient member.
48. The method of claim 1, wherein the back of the wafer is
contacted with said resilient member.
49. The method of claim 1, further comprising the steps of:
applying pressure to the resilient member to form a substantially
flat planar surface on the deformable material.
50. The method of claim 1, further comprising the steps of:
contacting the flexible resilient member with a substrate; and
applying pressure to the substrate thereby applying pressure to the
flexible resilient member.
51. The method of claim 47, further comprising the steps of:
applying pressure to the wafer by applying pressure to the flexible
resilient member thereby applying pressure to the object.
52. The method of claim 1, wherein said wafer includes a wafer
having a plurality of electrical circuit components on a surface
thereof.
53. The method of claim 1, wherein said wafer includes a wafer
having a plurality of electrical components on a surface thereof
and a coating substantially covering the electrical components.
54. The method of claim 1, wherein said wafer includes a wafer
having a plurality of electrical circuits on a surface thereof and
a coating substantially covering the electrical circuits and said
wafer.
Description
FIELD OF THE INVENTION
The present invention relates to the manufacturing of semiconductor
devices. More particularly, the present invention relates to an
improved chemical mechanical planarization process for the
planarization of surfaces in the manufacturing of semiconductor
devices.
BACKGROUND OF THE INVENTION
State of the Art
Typically, integrated circuits are manufactured by the deposition
of layers of predetermined materials to form the desired circuit
components on a silicon wafer semiconductor substrate. As the
layers are deposited on the substrate wafer to form the desired
circuit component, the planarity of each of the layers is an
important consideration because the deposition of each layer
produces a rough, or nonplanar, topography initially on the surface
of the wafer substrate and, subsequently, on any previously
deposited layer of material.
Typically, photolithographic processes are used to form the desired
circuit components on the wafer substrate. When such
photolithographic processes are pushed to their technological
limits of circuit formation, the surface on which the processes are
used must be as planar as possible to ensure success in circuit
formation. This results from the requirement that the
electromagnetic radiation used to create a mask, which is used in
the formation of the circuits of the semiconductor devices in wafer
form, must be accurately focused at a single level, resulting in
the precise imaging over the entire surface of the wafer. If the
wafer surface is not sufficiently planar, the resulting mask will
be poorly defined, causing, in turn, a poorly defined circuit which
may malfunction. Since several different masks are used to form the
different layers of circuits of the semiconductor devices on the
substrate wafer, any non-planar areas of the wafer will be
subsequently magnified in later deposited layers.
After layer formation on the wafer substrate, either a chemical
etch-back process of planarization, or a global press planarization
process typically followed by a chemical etch-bach process of
planarization, or chemical mechanical planarization process may be
used to planarize the layers before the subsequent deposition of a
layer of material thereover. In this manner, the surface
irregularities of a layer may be minimized so that subsequent
layers deposited thereon do not substantially reflect the
irregularities of the underlying layer.
One type of chemical etch-back process of planarization,
illustrated in EUROPEAN PATENT APPLICATION 0 683 511 A2, uses a
coating technique in which an object having a flat surface is used
to planarize a coating material applied to the wafer surface prior
to a plasma reactive ion etching process being used to planarize
the wafer surface. Often, however, the planarization surface will
contain defects, such as pits or other surface irregularities.
These may result from defects in the flat surface used for
planarizing or from foreign material adhering to the flat surface.
The etching of such a wafer surface having irregularities will, at
best, translate those undesirable irregularities to the etched
surface. Further, since some etching processes may not be fully
anisotropic, etching such irregular surfaces may increase the size
of the defects in the etched wafer surface.
One type of global press planarization process, illustrated in U.S.
Pat. No. 5,434,107, subjects a wafer with features formed thereon
having been coated with an inter-level dielectric material to an
elevated temperature while an elevated pressure is applied to the
wafer using a press until the temperature and pressure conditions
exceed the yield stress of the upper film on the wafer so that the
film will attempt to be displaced into and fill both the
microscopic and local depressions in the wafer surface. It should
be noted that the film is only deformed locally on the wafer, not
globally, during the application of elevated temperature and
pressure since the object contacting the surface of the wafer will
only contact the highest points or areas on the surface of the
wafer to deform or displace such points or areas of material on the
entire wafer surface. Other non-local depressions existing in the
wafer are not affected by the pressing as sufficient material is
not displaced thereinto. Subsequently, the temperature and pressure
are reduced so that the film will become firm again thereby leaving
localized areas having a partially planar upper surface on portions
of the wafer while other portions of the wafer surface will remain
non-planar.
In one instance, global planar surfaces are created on a
semiconductor wafer using a press located in a chamber. Referring
to drawing FIG. 1, a global planarization apparatus 100 is
illustrated. The global planarization apparatus 100 serves to press
the surface of a semiconductor wafer 120 having multiple layers
including a deformable outermost layer 122 against a fixed pressing
surface 132. The surface of the deformable layer 122 will assume
the shape and surface characteristics of the pressing surface 132
under the application of force to the wafer 120. The global
planarization apparatus 100 includes a fully enclosed apparatus
having a hollow cylindrical chamber body 112 having open top and
bottom ends 113 and 114, respectively, and interior surface 116 and
an evacuation port 111. A base plate 118 having an inner surface
117 is attached to the bottom end 114 of chamber body 112 by bolts
194. A press plate 130 is removably mounted to the top end 113 of
chamber body 112 with pressing surface 132 facing base plate 118.
The interior surface 116 of chamber body 112, the pressing surface
132 of press plate 130 and the inner surface 117 of base plate 118
define a sealable chamber. Evacuation port 111 can be positioned
through any surface, such as through base plate 118, and not solely
through chamber body 112.
The press plate 130 has a pressing surface 132 with dimensions
greater than that of wafer 120 and being thick enough to withstand
applied pressure. Press plate 130 is formed from non-adhering
material capable of being highly polished so that pressing surface
132 will impart the desired smooth and flat surface quality to the
surface of the deformable layer 122 on wafer 120. Preferably, the
press plate is a disc shaped quartz optical flat.
A rigid plate 150 having top and bottom surfaces 152 and 154,
respectively, and lift pin penetrations 156 therethrough is
disposed within chamber body 112 with the top surface 152
substantially parallel to and facing the pressing surface 132. The
rigid plate 150 is constructed of rigid material to transfer a load
under an applied force with minimal deformation.
A uniform force is applied to the bottom surface 154 of rigid plate
150 through the use of a bellows arrangement 140 and relatively
pressurized gas to drive rigid plate 150 toward pressing surface
132. Relative pressure can be achieved by supplying gas under
pressure or, if the chamber body 112 is under vacuum, allowing
atmospheric pressure into bellows 140 to drive the same. The
bellows 140 is attached at one end to the bottom surface 154 of
rigid plate 150 and to the inner surface 117 of base plate 118 with
a bolted mounting plate 115 to form a pressure containment that is
relatively pressurized through port 119 in base plate 118. One or
more brackets 142 are mounted to the inner surface 117 of the base
plate 118 to limit the motion toward base plate 118 of the rigid
plate 150 when bellows 140 is not relatively pressurized. The
application of force through the use of a relatively pressurized
gas ensures the uniform application of force to the bottom surface
154 of rigid plate 150. The use of rigid plate 150 will serve to
propagate the uniform pressure field with minimal distortion.
Alternately, the bellows 140 can be replaced by any suitable means
for delivering a uniform force, such as a hydraulic means.
A flexible pressing member 160 is provided having upper and lower
surfaces 162 and 164, respectively, which are substantially
parallel to the top surface 152 of rigid plate 150 and pressing
surface 132. Lift pin penetrations 166 are provided through member
160. The flexible member 160 is positioned with its lower surface
164 in contact with the top surface 152 of rigid plate 150 and lift
pin penetrations 166 aligned with lift penetrations 156 in rigid
plate 150. The upper surface 162 of the member 160 is formed from a
material having a low viscosity that will deform under an applied
force to close lift pin penetrations 166 and uniformly distribute
the applied force to the wafer, even when the top surface 152, the
upper surface 162 and/or the lower surface 164 is not completely
parallel to the pressing surface 132 or when thickness variations
exist in the wafer 120, rigid plate 150 or member 160, as well as
any other source of non-uniform applied force.
Lift pins 170 are slidably disposable through lift pin penetrations
156 and 166, respectively, in the form of apertures, to contact the
bottom surface 126 of wafer 120 for lifting the wafer 120 off the
top surface 162 of member 160. Movement of the lift pins 170 is
controlled by lift pin drive assembly 172, which is mounted on the
inner surface 117 of the base plate 118. The lift pin drive
assembly provides control of the lift pins 170 through conventional
means. Lift pins 170 and lift pin drive assembly 172 are preferably
positioned outside the pressure boundary defined by the bellows 140
to minimize the number of pressure boundary penetrations. However,
they can be located within the pressure boundary, if desired, in a
suitable manner.
A multi-piece assembly consisting of lower lid 180, middle lid 182,
top lid 184, gasket 186 and top clamp ring 188 are used to secure
the press plate 130 to the top end 113 of chamber body 112. The
ring-shaped lower lid 180 is mounted to the top end 113 of chamber
body 112 and has a portion with an inner ring dimension smaller
than press plate 130 so that press plate 130 is seated on lower lid
180. Middle lid 182 and top lid 184 are ring-shaped members having
an inner ring dimension greater than press plate 130 and are
disposed around press plate 130. Middle lid 182 is located between
lower lid 180 and top lid 184. A gasket 186 and top clamp ring 188
are members having an inner ring dimension less than that of press
plate 130 and are seated on the surface of press plate 130 external
to the chamber. Bolts 194 secure press plate 130 to the chamber
body 112.
Heating elements 190 and thermocouples 192 control the temperature
of the member 160.
In operation, the top clamp ring 188, gasket 186, top lid 84, and
middle lid 82 are removed from the body 112 and the press plate 130
lifted from lower lid 180. The bellows 140 is deflated and rigid
plate 150 is seated on stand off brackets 142. The wafer 120 is
placed on the flexible member 160 with the side of the wafer 120
opposite the deformable layer 122 in contact with flexible member
160. The press plate 130 is mounted on the lower lid 180 and the
middle lid 182, and upper lid 184 are installed and tightened using
gasket 186 and top clamp ring 188 sealing press plate 130 between
top clamp ring 188 and lower lid 180. The temperature of member
160, press plate 130, and rigid plate 150 are adjusted through the
use of heating elements 190 monitored by thermocouples 192 to vary
the deformation characteristics of the layer 122 of wafer 120.
Chamber body 112 is evacuated through port 119 to a desired
pressure.
A pressure differential is established between the interior and
exterior of the bellows 140, whether by pressurizing or by venting
when the chamber body 112 having been evacuated thereby drives
rigid plate 150, member 160, and wafer 120 toward press plate 130
and brings deformable layer 122 of wafer 120 into engagement with
pressing surface 132 of press plate 130. Upon engagement of wafer
120 with press plate 130, the continued application of force will
deform the flexible member 160 which, in turn, serves to close lift
penetrations 166 and distribute the force to ensure the wafer 120
experiences uniform pressure on its surface 122. After the wafer
120 has been in engagement with pressing surface 132 for a
sufficient time to cause surface 122 to globally correspond to the
pressing surface layer 132, the surface 122 is hardened or cured.
The pressure is released from the bellows 140, thereby retracting
wafer 120, member 160, and rigid plate 150 from the press plate
130. The downward movement of rigid plate 150 will be terminated by
its engagement with stand off offset brackets 142.
Once the rigid plate 150 is fully retracted, the vacuum is released
in chamber body 112. Lift pins 170 are moved through lift
penetrations 156 in the rigid plate 150 and lift penetrations 166
in the member 160 to lift wafer 120 off the member 160. The top
clamping ring 188, gasket 186, top lid 184, middle lid 182, and
press plate 130 are removed and the wafer 120 is removed off lift
pins 170 for further processing.
Once the wafer is removed, it will be subjected to an etch to
establish the planar surface at the desired depth. A system used or
depicted in FIG. 1 provides an optimal method of deforming a
flowable, curable material to form a generally planarized surface.
However, the method is still subject to yielding a wafer surface
with irregularities therein, and the need for the subsequent etch
to define the desired surface height will still result in
undesirable transfer and possible enlargement of any such surface
irregularities.
Conventional chemical mechanical planarization processes are used
to planarize layers formed on wafer substrates in the manufacture
of integrated circuit semiconductor devices. Typically, a chemical
mechanical planarization (CMP) process planarizes a non-planar
irregular surface of a wafer by pressing the wafer against a moving
polishing surface that is welted with a chemically reactive,
abrasive slurry. The slurry is usually either basic or acidic and
generally contains alumina or silica abrasive particles. The
polishing surface is usually a planar pad made of a relatively
soft, porous material, such as a blown polyurethane, mounted on a
planar platen.
Referring to drawing FIG. 2, a conventional chemical mechanical
planarization apparatus is schematically illustrated. A
semiconductor wafer 112 is held by a wafer carrier 111. A soft,
resilient pad 113 is positioned between the wafer carrier 111 and
the wafer 112. The wafer 112 is held against the pad 113 by a
partial vacuum. The wafer carrier 111 is continuously rotated by a
drive motor 114 and is also designed for transverse movement as
indicated by the arrows 115. The rotational and transverse movement
is intended to reduce variability in material removal rates over
the surface of the wafer 112. The apparatus further comprises a
rotating platen 116 on which is mounted a polishing pad 117. The
platen 116 is relatively large in comparison to the wafer 112, so
that during the chemical mechanical planarization process, the
wafer 112 may be moved across the surface of the polishing pad 117
by the wafer carrier 111. A polishing slurry containing a
chemically reactive solution, in which abrasive particles are
suspended, is delivered through a supply tube 121 onto the surface
of the polishing pad 117.
Referring to drawing FIG. 3 a typical polishing table is
illustrated in top view. The surface of the polishing table 1 is
precision machined to be flat and may have a polishing pad affixed
thereto. The surface of the table rotates the polishing pad past
one or more wafers 3 to be polished. The wafer 3 is held by a wafer
holder, as illustrated hereinbefore, which exerts vertical pressure
on the wafer against the polishing pad. The wafer holder may also
rotate and/or orbit the wafer on the table during wafer
polishing.
Alternately, the table 1 may be stationary and serve as a
supporting surface for individual polishing platens 2, each having
their own individual polishing pad. As illustrated in U.S. Pat. No.
5,232,875, each platen may have its own mechanism for rotating or
orbiting the platen 2. A wafer holder will bring a wafer in contact
with the platen 2 and an internal or external mechanism to the
wafer holder may be used to also rotate the wafer during the
polishing operation. In a polishing table having multiple
individual platens, each platen must be precision machined.
The wafers 3 are typically stored and transported in wafer
cassettes which hold multiple wafers. The wafers 3 or wafer holders
are transported between the wafer cassettes and the polishing table
1 using the wafer transport arm 4. The wafer transport arm 4 will
transport the wafers 3 between the polishing table and the stations
5, which may be wafer cassette stations or wafer monitoring
stations.
The polishing characteristics of the polishing pad will change
during use as multiple wafers 3 are polished. The glazing or
changing of the polishing characteristics will affect the
planarization of the surface of the wafers 3 if the pads are not
periodically conditioned and unglazed. The pad conditioner 6 is
used to periodically unglaze the surface of the polishing pad. The
pad conditioner 6 has a range of motion which allows it to come in
contact with the individual pads and conduct the periodic unglazing
and then to move to its rest position.
The pressure between the surface of the wafer to be polished and
the moving polishing pad may be generated by either the force of
gravity acting on the wafer and the wafer carrier or by mechanical
force applied normal to the wafer surface. The slurry may be
delivered or injected through the polishing pad onto its surface.
The planar platens may be moved in a plane parallel to the pad
surface with either an orbital, fixed-direction vibratory or random
direction vibratory motion.
While a chemical mechanical planarization process is an effective
process to planarize the surface of a wafer, variations in height
on the surface to be planarized by the chemical mechanical
planarization process, although minimized through the chemical
mechanical planarization process, will often not be completely
removed to yield an optimally planar surface. As is well known in
the art, the chemical mechanical planarization process polishing
pad will deform, or "dish", into recesses between structures of the
surface of the wafer. The structure spacing on the wafer which will
yield this "dishing" is clearly a function of various factors, such
as the pad composition, the polishing pressure, etc. This pad
"dishing" will clearly lead to less than optimal planarization of
the surface of the wafer. Further, the surface irregularities
extending into or down to the wafer surface being planarized tend
to collect slurry, thereby causing such areas of the wafer to be
subjected to the corrosive effects of the slurry longer than other
areas of the wafer surface which do not collect the slurry.
To help minimize polishing pad deformation (dishing) caused by
surface irregularities formed by the integrated circuit components
on the wafer surface, dummy structures have also been included on
the wafer surface in an attempt to provide a more uniform spacing
of structures on the wafer surface. While the use of such dummy
structures will often be useful, the ultimate result is also highly
dependent upon the later chemical mechanical planarization process
conditions.
Therefore, a need exists to reduce the surface irregularities on a
wafer before the chemical mechanical planarization process to
facilitate planarization of the wafer surface irregularities by
such process and to facilitate planarization which provides greater
latitude in the chemical mechanical planarization process
parameters.
SUMMARY OF THE INVENTION
The present invention relates to an improved chemical mechanical
planarization process for the planarization of surfaces in the
manufacturing of semiconductor devices. The improved chemical
mechanical planarization process of the present invention includes
the formation of a flat, planar surface from a deformable, planar
coating on the surface of the wafer filling the areas between the
surface irregularities prior to the planarization of the surface
through a chemical mechanical planarization process.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of a global planarization apparatus;
FIG. 2 is an illustration of a conventional rotational chemical
mechanical planarization apparatus;
FIG. 3 is an illustration of a top view of a polishing table of a
conventional rotational chemical mechanical planarization
apparatus;
FIG. 4 is a cross-sectional view of a portion of a wafer substrate
having electrical circuit components formed thereon with a coating
thereover;
FIG. 5 is a cross-sectional view of a portion of a wafer substrate
having electrical circuit components formed thereon, a coating
thereover, a deformable coating, and a portion of a flat pressing
member used in the present invention;
FIG. 6 is a cross-sectional view of a portion of a wafer substrate
having electrical circuit components formed thereon, a coating
thereover, and a deformable coating after the deformation thereof
using a flat pressing member in the process of the present
invention;
FIG. 7 is a cross-sectional view of a portion of a wafer substrate
having electrical circuit components formed thereon and a coating
material between the electrical circuit components after the
chemical mechanical planarization process of the present invention
of the configuration illustrated in drawing FIG. 6;
FIG. 8 is a cross-sectional view of a portion of a wafer substrate,
a resilient member located below the resilient substrate, a support
member located below the wafer member and electrical circuit
components formed on the wafer substrate, a coating located over
the electrical circuits, and a deformable coating located over the
coating formed over the electrical circuits after the deformation
thereof using a flat pressing member in the process of the present
invention;
FIGS. 9A and 9B are a process flow description of the improved
chemical mechanical planarization process of the present invention
as illustrated in FIG. 7; and
FIGS. 10A and 10B are a process flow description of the improved
chemical mechanical planarization process of the alternative
embodiment of the present invention illustrated in drawing FIG.
8.
DESCRIPTION OF THE INVENTION
Referring to drawing FIG. 4, a portion of a wafer substrate 20 is
illustrated having portions of electrical circuit components 22
formed thereon and a coating of material 24, typically a metallic
material, a semiconductor material, or an insulating material 24,
covering the electrical circuit components 22 and portions of the
wafer substrate 20 located between the electrical circuit
components 22. As illustrated, the portions of the electrical
circuit components 22 are formed having upper surfaces 26 thereon
while the coating of insulating material 24 is formed having an
irregular nonplanar surface 28 extending over the surfaces 26 of
the electrical circuit components 22. The insulating coating
material 24 typically comprises an insulating oxide or other
dielectric material and may include a plurality of layers of such
insulating or other types of material, as desired. In this
instance, for convenience, the insulating material 24 is
illustrated covering the wafer substrate 20 and the electrical
circuit components 22 thereon regardless of the number of layers
thereof.
It can be easily seen that if only portions of the surface 28 of
insulating material 24 are removed for the formation of additional
electrical circuit components, the nonplanar surface of the
insulating material 24 would cause masking and etching problems as
the masking of the insulating material 24 as well as the etching
thereof would not be uniform. Therefore, the surface 28 must be
globally planarized to facilitate further electrical circuit
component formation.
At this juncture, if a conventional chemical mechanical
planarization process is used on the wafer substrate 20, the
surface of the wafer will be subject to a reactive slurry and one
or more polishing pads used in the process in an attempt to form a
planar surface on the insulating material 24 covering the
electrical circuit components 22. Some of the problems associated
with such a conventional chemical mechanical planarization process
are that the reactive slurry is unevenly distributed about the
wafer substrate 20 and the pad used in the process, that
particulates removed from the substrate 20 and insulating material
24 during the polishing process may become lodged in the polishing
pad forming a glaze thereon, thereby affecting the rate of removal
by the pad and causing the polishing pad to unevenly remove
material during the process, and that as the chemical mechanical
planarization process begins by polishing an irregular surface on
the wafer, such surface causes the deformation of the polishing pad
(dishing), thereby further inducing irregularities not initially
present in the surface being polished, the induced irregularities
of the surface of the wafer during the chemical mechanical
planarization of the wafer surface being caused by the dishing of
the polishing pad from the force applied thereto and the
deformation of the pad by surface areas of the wafer. Therefore,
before starting the chemical mechanical planarization process of
the surface of a wafer, it is desirable to have the surface to be
planarized as nearly planar as possible to help ensure the even
removal of material therefrom and to help eliminate the deformation
of the polishing pad(s) being used to thereby, in turn, help
minimize any surface irregularities being introduced into the
surface being planarized by such pad deformation.
Referring to drawing FIG. 5, the improved chemical mechanical
planarization process of the present invention is illustrated in
relation to a wafer substrate 20 having electrical circuit
components 22 thereon and a coating of insulating material 24
thereover. In the improved chemical mechanical planarization
process of the present invention, prior to the initiation of the
chemical mechanical planarization of the substrate 20, electrical
circuit components 22 and insulating material 24, a layer of
deformable material 30 is coated or deposited over the insulating
material 24. The deformable material 30 may be of any suitable type
material that readily flows over the surface 28 of the insulating
material 24 and that is subsequently solidified through curing or
hardening or other type of solidification. Alternately, the
deformable material 30, in some instances, may be a readily
deformable metal capable of being deformed under low temperature
and low pressure which may be readily deposited over the insulating
material 24 through well known techniques and processes. Whatever
the type of deformable material 30, the deformable material 30 is
applied over the insulating material 24 to any desired depth but is
typically applied in a thickness greater than the thickness of the
surface typography of the wafer, the thickness of the deformable
material 30 initially applied to the wafer depending upon the type
of material selected for such use, the dimensions of the surface
irregularities, etc. After the application of the layer of
deformable material 30 to the insulating material 24 and before the
material 30 has cured, hardened, or solidified to the point which
it is not capable of being deformed, an object 32 having a flat
planar surface 34 thereon is forced under pressure into the
deformable material 30 to form a flat, planar surface 36 thereon
and is kept in contact with the deformable material 30 while the
deformable material 30 cures, hardens, or solidifies. The object 32
may be of any well known suitable material, such as an optical
quartz glass disc shaped object, having a desired flat, planar
ground surface thereon which may be used to be pressed into the
deformable material 30 to form a flat, planar surface 36 thereon.
If desired, the object 32 may be tailored to meet process
requirements of the desired range of pressure to be applied to the
deformable material 30 and the method of curing, hardening or
solidifying the material 30. Further, if desired, the surface 34 on
the object 32 may have a shape other than a flat, planar surface
34, such as either a concave surface, convex surface, concave and
convex surface, or any type desired surface suitable in a chemical
mechanical planarization process. Additionally, the surface 34 of
the object 32 may be coated with a suitable release agent coating
to facilitate its removal from the deformable coating material 30
after the curing, hardening or solidification thereof.
The deformable material 30 may be any suitable well known organic
type, such as monomers, monomer mixtures, oligomers, and oligomer
mixtures that are solidified through curing. Alternately, the
deformable material 30 may be any suitable type epoxy resin which
may be cured using an acid catalyst.
The object 32 is kept through the application of suitable pressure
thereto, or application of pressure to the wafer substrate 20, or
the application of pressure to both the object 32 and the wafer
substrate 20 in engagement with the deformable material 30 until
such material has hardened or solidified to form a permanent flat,
planar surface 36 thereon being the mirror image of the flat,
planar surface 34 on the object 32. At such time, the object 32 is
removed from engagement with the deformable material 30.
Referring to drawing FIG. 6, before the chemical mechanical
planarization process of the present invention commenced the wafer
substrate 20 having electrical circuit components 22 and insulative
material 24 thereon is illustrated having the deformable material
30 having a flat, planar surface 36 thereon providing a global
flat, planar surface on the wafer substrate. As illustrated, the
global surface 36 on the deformable material 30 is a flat, planar
surface from which the chemical mechanical planarization process is
to begin on the wafer substrate 20. In this manner, a conventional,
well known chemical mechanical planarization process as described
hereinbefore can be used to form flat planar surfaces on the
insulating material 22. By starting with a globally flat, planar
surface 36 on the deformable material 30, any deformation of the
pad 117 (FIG. 2) is minimized. Also, any non-uniform planarization
which may occur due to the uneven distribution of the chemical
reactive solution and abrasives included therein or material
particles from the surfaces being planarized being collected or
present in the pad 117 resulting from surface irregularities is
minimized. In this manner, by starting the chemical mechanical
planarization process from a globally flat, planar surface 36 of
the deformable material 30, as the chemical mechanical
planarization process is carried out, the surfaces of the layers
being planarized remain flat and planar because the pad 117 is
subjected to more uniform loading and operation during the process.
This is in clear contrast to the use of a chemical mechanical
planarization process beginning from an irregular nonplanar surface
as is typically carried out in the prior art.
Referring to drawing FIG. 7, illustrated is a wafer substrate 20,
electrical circuit components 22 and insulating layer 24 which have
been planarized using the improved chemical mechanical
planarization process of the present invention. As illustrated, a
flat, planar surface 40 has been formed through the use of the
chemical mechanical planarization process of the present invention
as described hereinbefore with the surface 40 including flat planar
surface 28' of the insulating material 24.
Referring to drawing FIG. 8, an alternate apparatus and method of
the improved chemical mechanical planarization process of the
present invention is illustrated. The present invention is
illustrated in relation to a wafer substrate 20 having electrical
circuit components 22 thereon and a coating of insulating material
24 thereover. In the improved chemical mechanical planarization
process of the present invention, prior to the initiation of the
chemical mechanical planarization of the wafer substrate 20,
electrical circuit components 22 and insulating material 24, a
layer of deformable material 30 is coated or deposited over the
insulating material 24. The deformable material 30 may be of any
suitable type material which readily flows over the surface 28 of
the insulating material 24 that is subsequently solidified through
curing or hardening. The deformable material 30 is applied over the
insulating material 24 to any desired depth but is typically
applied in a thickness greater than the surface typography of the
wafer, the thickness of the deformable material 30 initially
applied to the wafer depending upon the type of material selected
for such use, the dimensions of the surface irregularities,
etc.
After the application of the layer of deformable material 30 to the
insulating material 24 and before the material 30 has cured,
hardened, or solidified to the point which it is not capable of
being deformed, a flexible resilient member 50 is placed under the
wafer substrate 20 between the wafer substrate 20 and the substrate
60 on which the wafer substrate 20, is supported and, an object 32
having a flat planar surface 34 thereon is forced under pressure
into surface 36 of the deformable material 30 to form a globally
flat, planar surface 36 thereon and is kept in contact with the
deformable material 30 while the deformable material 30 cures,
hardens, or solidifies. As previously illustrated, the object 32
may be of any well known suitable material, such as an optical
quartz glass disc shaped object having a flat, planar ground
surface thereon which may be used to be pressed into the deformable
material 30 to form a globally flat, planar surface 36 thereon. If
desired, the object 32 may be tailored to meet process requirements
of the desired range of pressure to be applied to the deformable
material 30 and the method of curing, hardening or solidifying the
material 30.
Further, if desired, the surface 34 of the object 32 may have a
shape other than a flat, planar surface 34, such as either a
concave surface, convex surface, or any desired surface.
Additionally, the surface 34 of the object 32 may be coated with a
suitable release agent coating to facilitate its removal from the
deformable coating material 30 after the curing, hardening or
solidification thereof. The flexible resilient member 50 comprises
a suitably shaped member compatible with the wafer substrate 20
formed of resilient material which will deform under an applied
force to uniformly distribute the applied force from the object 32
to the deformable material 30, even if the surface 34 of object 32,
surfaces 52 and 54 of the member 50 and the surface 36 of the
deformable material 30 on wafer substrate 20 are not substantially
parallel to each other or, alternately, when thickness variations
locally exist within either the wafer substrate 20, electrical
circuit components 22, insulative material 24, object 32, and/or
flexible resilient member 50. It is preferred that the flexible
resilient member 50 is thermally stable and resistant to the
temperature ranges of operation experienced during the pressing by
object 32 and that the member 50 be formed from a low viscosity and
low durometer hardness material. In this manner, the flexible
resilient member 50 serves to compensate for the variations in the
thickness of the wafer substrate 20, electrical circuit components
22, insulating material 24, deformable material 30, and object 32
as well as compensating for any non-parallel surfaces on the object
32 or the wafer substrate 20 or the substrate 60 on which the wafer
substrate 20 is supported during the pressing of object 32 to form
planar surface 36 on the deformable material 30 prior to the
beginning of the chemical mechanical planarization process
thereafter. The preferable manner in which the insulating material
24 on a wafer substrate 20 is to be globally planarized to have a
globally flat, planar surface 28 to begin the chemical mechanical
planarization process is to use the global planarization apparatus
100 hereinbefore described with respect to drawing FIG. 1, or its
equivalent.
Referring to drawing FIGS. 9A and 9B, the improved chemical
mechanical planarization process of the present invention as
described hereinbefore is illustrated in a series of process steps
202 through 218.
In process step 202, a wafer substrate 20 is provided having
electrical circuitry components 22 formed thereon and an insulating
material coating 24 covering the components 22 and portions of the
wafer substrate 20.
In process step 204, a coating of deformable material 30 which is
uncured, unhardened, or not solidified at the time of application
is applied to the coating of insulating material 24 to cover the
same.
Next, in process step 206, an object 32 having a flat planar
surface 34 thereon is provided for use.
In process step 208, the surface of deformable material 30 is
contacted by the flat, planar surface 34 of the object 32.
In process step 210, a predetermined level of pressure is applied
at a predetermined temperature level to the deformable material 30.
The pressure may be applied to either the object 32, the substrate
20, or both, etc.
In process step 212,flat, planar surface 34 of object 32 forms a
flat, planar surface 36 on the deformable material 30.
In process step 214, while the flat, planar surface 34 of the
object 32 engages the deformable material 30 thereby forming the
flat, planar surface 36 thereon, the deformable material 30 is
cured, hardened, or solidified to cause the permanent formation and
retention of the flat, planar surface 36 on the deformable material
30.
In process step 216, the object 32 is removed from engagement with
the deformable material 30 after the curing, hardening or
solidification thereof to retain the flat, planar surface 36
thereon.
In process step 218, the wafer substrate 20 having electrical
circuit components 22, insulating coating 24, and cured, hardened,
or solidified deformable material 30 thereon is subjected to a
suitable chemical mechanical planarization process until the upper
surfaces 26' of the electrical circuit components and surface 28'
of the insulating material 24 are a concurrent common flat, planar
surface extending across the wafer substrate 20 (see FIG. 7).
Referring to drawing FIGS. 10A and 10B, alternately, if the
apparatus and method described with respect to drawing FIG. 8 are
used, the process of such improved chemical mechanical
planarization process is illustrated in process steps 302 through
320.
In process step 302, a wafer substrate 20 is provided having
electrical circuitry components 22 formed thereon and an insulating
material coating 24 covering the components 22 and portions of the
wafer substrate 20.
In process step 304, a coating of deformable material 30 which is
uncured, unhardened, or not solidified at the time of application
is applied to the coating of insulating material 24 to cover the
same.
Next, in process step 306, an object 32 having a flat planar
surface 34 thereon is provided for use.
In process step 308, a flexible resilient member 50 is placed in
contact with the bottom surface of the wafer substrate 20.
In process step 310, the surface 36 of the deformable material 30
is contacted with the surface 34 of the object 32.
In process step 312, flexible resilient member 50 remains
contacting or engaging the bottom surface of the wafer substrate
20.
In process step 314, a predetermined level of pressure is applied
at a predetermined temperature level to either the object 32, or
the wafer substrate 20, or both, thereby causing the flat, planar
surface 34 of the object 32 to transmit force to the deformable
material 30, thereby causing the surface 36 of the deformable
material 30 to form a flat planar surface thereon substantially
similar to the flat planar surface 34 of the object 32.
In process step 316, while the flat, planar surface 34 of the
object 32 engages the deformable material 30, thereby forming the
flat, planar surface 36 thereon, the deformable material 30 is
cured, hardened or solidified to cause the permanent formation and
retention of the flat, planar surface 36 on the deformable material
30.
In process step 318, the object 32 is removed from engagement with
the deformable material 30 after the curing, hardening or
solidification thereof to retain the flat, planar surface 36
thereon. If the flexible member 50 is used on the bottom of the
wafer substrate 20, it may remain, or, if desired, a comparable
flexible member may be provided during the chemical mechanical
planarization process.
In process step 320, the wafer substrate 20 having electrical
circuit components 22, insulating coating 24, and cured, hardened,
or solidified deformable coating 30 thereon is subjected to a
suitable chemical mechanical planarization process until the upper
surfaces 26' of the electrical circuit components and surface 28'
of the insulating material 24 are a concurrent, common, unbroken
flat, planar surface 40 extending across the wafer substrate 20
(see FIG. 7). The preferable manner in which the coating 24 on a
wafer substrate 20 is to be globally planarized to have a globally
flat, planar surface 28 to begin the chemical mechanical
planarization process is to use the global planarization apparatus
100 hereinbefore described with respect to drawing FIG. 1, or its
equivalent.
In this manner, when the improved process of chemical mechanical
planarization of the present invention is used, the resulting
planarized surface on the wafer substrate is globally planar or
more planar since the process started from a globally flat, planar
surface and the chemical mechanical planarization process reaches a
successful conclusion more quickly because the surface being
planarized does not deform the polishing pad unnecessarily as the
surface remains substantially planar throughout the process. This
is in clear contrast to the prior art conventional chemical
mechanical planarization process which begins from an irregular
nonplanar surface, thereby causing the deformation and deflection
of the polishing pad, thereby, in turn, causing an irregular
nonplanar surface in the surface being planarized. Furthermore, the
improved chemical mechanical planarization process of the present
invention offers advantages over a globally planarized surface
which is subsequently dry resistant etched-back. In globally
planarized surfaces which are dry etched-back, the dry etching
process does not act uniformly on the materials being etched as
they are subjected to the etching process at differing times and
each material exhibits a differing etching rate, thereby causing
irregularities to be present in the resulting final surface at the
end of the dry etching process. In contrast, the improved chemical
mechanical planarization process begins from a globally flat planar
surface, retains a globally flat, planar surface throughout the
process, and results in a final globally flat planar surface at the
end of the process.
It will be understood that changes, additions, modifications, and
deletions may be made to the improved chemical mechanical
planarization process of the present invention which are clearly
within the scope of the claimed invention.
* * * * *